99999...99999 (221-digits)
This number is a prime.
9 9999999999
9999999999 9999999999 9999999999 9999999999 9999999999 9999999999 9899999999
9999999988 8999999999 9999999881 8899999999 9999999988 8999999999 9999999899
9999999999 9999999999 9999999999 9999999999 9999999999 9999999999 9999999999
The largest diamond-congruent prime of order 11. [Patterson]
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